An implementation of Karplus-Strong Algorithm in C. Using /dev/urandom in linux.

kpa.c

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <time.h>

#define SECONDS 6  /* you can change this to suit for your preferences */
#define LENGTH 300 /* you can experiment with different string length */

char wav_struct[] = {
  'R', 'I', 'F', 'F',
   0,   0,   0,   0,  /* chunksize */
  'W', 'A', 'V', 'E',
  'f', 'm', 't', ' ', /* subchunk1id */
   16,  0,   0,   0,  /* subchunk1size */
   1,   0,            /* audioformat */
   1,   0,            /* numchannels */
   68,  172, 0,   0,  /* samplerate 44100 */
   136, 88,  1,   0,  /* byterare 88200 */
   2,   0,            /* blockalign */
   16,  0,            /* bitspersample */
  'd', 'a', 't', 'a', /* subchunk2id */
   0,   0,   0,   0   /* subchunk2size */


};

int main(){
   int16_t wavetable[LENGTH];
   srand(time(NULL));
   for (int i = 0; i < LENGTH; i++) wavetable[i] = rand();

   int16_t *raw_pcm = malloc(sizeof(int16_t)*44100*SECONDS);
   if (raw_pcm == NULL){
      fprintf(stderr, "Failed to allocated raw_pcm\n");
      return 1;
   }
   int previous = 0;
   int current = 0;
   for (int i = 0; i < 44100*SECONDS; i++){
      wavetable[current] = ((wavetable[current]/2)+(previous/2));
      raw_pcm[i] = wavetable[current];
      previous = raw_pcm[i];
      current += 1;
      current %= LENGTH;
   }

   FILE *fpout = fopen("kpa.wav", "wb");
   if (fpout == NULL) {
      fprintf(stderr, "Couldn't write kpa.wav\n");
      free(raw_pcm);
      return 1;
   }
   fwrite(wav_struct, sizeof(wav_struct), 1, fpout);
   fwrite(raw_pcm, sizeof(int16_t), 44100*SECONDS, fpout);

   uint32_t length = 32+((44100*SECONDS)<<1);
   fseek(fpout, 4, SEEK_SET);
   fwrite(&length, sizeof(uint32_t), 1, fpout);

   uint32_t subchunk2size = (44100*SECONDS)<<1;
   fseek(fpout, 40, SEEK_SET);
   fwrite(&subchunk2size, sizeof(uint32_t), 1, fpout);

   fclose(fpout);

   free(raw_pcm);
   return 0;


}